Fuze assembly



April 2 60 2 Sheet et 1 Filed Feb 2' 6 N E 5 ms O N E a V n ma M s 6 w R E m M M N V c o w W A April 26, 1960 c. 1 2. OLSEN 2,934,019

FUZE ASSEMBLY Filed Feb. 2, 1956 2 Sheets-Sheet 2 56 2' 7 V W W H Jj/ll/l/ ////1////// V no in:

32 54 so as. 48

INVENTOR. CHARLES R. OLSEN United States Patent FUZE ASSEMBLY Charles R. Olsen, Cincinnati, Ohio, assignor to the United States of America, as represented by the Secretary of the Navy Application February 2, 1956, Serial No. 563,167

3 Claims. (Cl. 102--78) (Granted under Title 35, US. Code (1952), see. 266) The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.

This invention relates to delayed arming fuze assemblies for missiles or projectiles and more particularly to such assemblies having double safe arming mechanisms in which diverse parts must move in both longitudinal and rotary motion to effect complete arming of the assemblies.

Premature arming and detonation of the warheads of missiles or projectiles has presented a continuing problem in the field of ordnance. Many devices have been developed for arming the warheads of such projectiles at a given delay time after firing and in each case, of course, there has been incorporated an attempt to prevent arming prior to firing or too soon after firing. Such devices have reached a stage of comparatively successful development, and generally include an acceleration or rotation responsive device responsive to continued acceleration or rotation for a given time to arm the device. However, the means to prevent premature arming due to rough handling or accidental dropping have not always been capable of preventing such premature arming with the attendant misfirings and danger to personnel and equipment. In general, such devices have involved either so long a timing motion as to theoretically preclude accidental arming when combined with a return spring arrangement, or they have included elements having rotary or longitudinal motion in response to acceleration on firing which are locked against movement and have socalled set-back means responsive to initial firing to release the elements for movement to arm the fuzes. In each case the safety feature appears to be dependent upon restraint of only one type of motion.

The present invention provides a fuze mechanism which has a notably greater degree of protection against premature or accidental arming than has hitherto been possible. This greater degree of protection is made possible by a novel arming means comprising a plurality of means responsive to acceleration forces in different types of motion (i.e., rotary and longitudinal) which must each be released and operated through a time delay by forces caused by changes in speed occurring in the conveying missile as it accelerates on firing and decelerates in flight. Thus, arming is not possible unless both such means have completed the arming cycle. The possibility of rough handling, dropping, etc., causing accidental completion of two arming cycles (which have diiferent types of motion) to complete such a cycle is obviously much less than the possibility of a single such means completing its arming cycle accidentally.

It is therefore an object of this invention to provide fuze assemblies having novel arming mechanisms which have an improved factor of safety against premature and accidental arming.

It is a further object of this invention to provide novel I 2,934,019 Patented Apr. 26, 1960 fuze assemblies having a plurality of time delay means in the arming mechanism thereof, each of which must complete a time delay cycle to arm the fuze whereby the danger of premature or accidental arming is lessened.

It is a still further object of this invention to provide fuze assemblies having a plurality of time delay devices in the arming mechanism thereof, said means having diverse natures of motion in the arming mechanism, each of which must complete a time delay cycle to arm the fuze whereby the danger of premature or accidental arming in dropping or other rough handling is minimized.

Other objects and many of the attendant advantages of this invention will be readily appreciated as the'same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings wherein:

Fig. 1 is a sectional View of a portion of a warhead embodying the novel fuze assembly of the present invention;

Fig. 2 is a front elevational view of the novel arming mechanism which forms a portion of the warhead of Fig. 1, with the forward portion of the outer case thereof removed (and shown in section) to allow clearer illustration of the parts, the fuze mechanism being shown Fig. 4 is a view similar to Figs. 2 and 3 showing the fuze mechanism fully armed with the parts in the positions assumed after completion of the period of acceleration of the conveying missile.

Attention is now directed to the drawings wherein like reference characters designate like or corresponding parts throughout the several views, and wherein Fig. 1 depicts an exemplary application of the fuze mechanism of the present invention to a warhead. The fuze mechanism is obviously adapted for incorporation in the nose or tail or in various other positions in warheads and missiles and the specific illustrated setting of Fig. 1 is purely by way of example. Fig. 1 shows the fuze mechanism of the present invention as used within the body of the Warhead of a missile, the reference numeral 2 denoting the outer casing of the warhead and the reference numeral 4 the high explosive charge contained therein between the rearward end of the warhead (not shown). The forward end of the casing is provided with a shaped charge cone or retaining wall 6 to enclose the explosive charge 4 and which has a central opening to which is attached the open end of a cylindrical container 8 which extends rearwardly from the wall 6 into the charge 4 to serve as a housing for the arming mechanism A, as shown. Casing 2 is screw threaded at its forward portion, as at 10, for connection to the usual ogival nose piece (not shown) of the missile. In practice, the structure so far described is formed by securing the shaped charge cone 6 with its attached housing 8 in the forward end of easing 2, as shown, by any suitable means, as by welding. Explosive charge 4 is then loaded into the casing 2 from the rear end thereof, as by pouring, for example, and the casing is then sealed.

Arming mechanism A, comprises an outer case 12 of an external diameter substantially similar to the internal diameter of the housing 8 and therefore adapted to be positioned by sliding insertion into said housing.

A cylindrical sleeve member 14 of a size to engage the inner walls of the case 12 is mounted for sliding motion within said case. Sleeve member 14 is of hollow construction, with a substantially closed forward end wall 16 having a centrally located passage 18 therethrough, as shown. The hollow interior of sleeve 14 and the passage 18 are filled with a booster pellet 20 of explosive material of a nature to explode when ignited to cause detonation of the explosive 4 in the warhead and fragmentation of the warhead. Pellet 2%) is formed with a cup-like depression in the rear end thereof, as shown in Fig. l and this cupped after end of the pellet is sealed by a thin metallic shield 22. A similar metallic shield 24 is used to seal the forward end of the pellet, within the passage 18.

A rotary arming device R is fixedly mounted on the forward wall of sleeve member 14 by any suitable means, as by screw means, as shown in Fig. 1 and thus moves with said sleeve member. Arming device R is one of a well-known family of arming devices in which an unbalanced rotor member 26 is caused to rotate from unarmed to armed position by acceleration forces. Such rotors commonly have a bore 28 extending therethrough, said bore containing a primer means and a suitable igniting train 30. The normal unarmed position of arming device R is with rotor 26 disposed as in Fig. l with the bore 28 and its primer means 30 out of alignment with initiating means (to be later described) and out of alignment with the opening 18 of the forward wall 16 of the booster containing sleeve member 14. The details of such a fuze are not of the essence of this invention and are accordingly not illustrated or specifically described in this disclosure, it being deemed sufficient to identify it as a well known and commonly used type having a rotor as described and releasable locking means to prevent premature rotation of said rotor. An example of this family of fuzes is illustrated in the copending patent application of Winifred E, Sapp, Serial No. 342,039, filed March' 12, 1953 in the United States Patent Oflice;

Sleeve member 14 is provided with guide groove means 32 on opposed external surfaces to cooperate with internally projecting pins 34 attached to or forming a part of the outer case 12 of the arming mechanism A. As may be best seen by reference to Fig. l, grooves 32 may be formed by being etched or otherwise cut into the external wall of sleeve 14 a depth less than the thickness of the wall so that the remaining wall thickness serves to retain and preserve the booster explosive. Grooves 32 are in the shape illustrated in Figs. 2, 3 and 4 and each comprises an elongated portion 36 which may extend and open into the rear of the sleeve 14 and which is of zigzag conformation and of a size relative to that of the associated -pin 34 such as to compel the pin to follow a similar Zig-zag path upon relative movement of sleeve 14 relative to the outer case 12. Elongated path 36 opens at its forward end into an elongated groove section 38 which is of V configuration and which serves as the terminus of a shorter zig-zag portion 40, the arrangement being such that if the pins 34 are disposed as shown in Fig. 2 rearward motion of the sleeve will cause it to move relative to pins 34 to the position shown in Fig. 3 and any subsequent forward motion of the sleeve will result in the pins 34 being disposed in the elongated path 34 of groove 32 and the sleeve following a course of motion directed and limited thereby. This latter sequence of motion is assisted and compelled by the fact that the forward extremity of one wall 42.of path 36 of the groove is formed in a straight line as shown, to substantially overlie the point forming the forward terminal of groove 32, in the section 38 thereof.

Case 12 has a suitably fastened closure member 44 at the rear end thereof, said closure member having an attached central stake 46 which serves to position a spring member 48 (designated a setback spring) which extends into the depression 21 in the booster grain 20 and in its metallic seal 22 to exert a forward pressure on the sleeve 14 through the grain 20. It is thus obvious that, with the assembly in the position of Fig. 2, the spring 48 tends to hold the sleeve and its attached part in this position with pins 34 against the rear terminal end of the short groove sections 40. Then, if the application of a force causes the assembly to be moved rearwardly against the pressure of spring 48 until pin 34 strikes the forward end of section 38 of the groove and the force is removed, the spring will tend to move the sleeve forward and pin 34 will strike wall 42 and enter the elongated path 36 to direct the motion of sleeve 14 accordingly, and the time required for the sleeve to traverse the length of the path may be regulated by the strength of the spring 48 and the length and abruptness of the angular portions of zig-zag groove 36.

The forward end of the outer case 12 of the arming mechanism is sealed by a closure or wall member 50 secured by any suitable means to said case 12. Closure 50 has a central opening through which an electrical contact 52 passes. Contact 52 is fixedly positioned by being embedded in a plastic insulating material 54 which seals the central opening in the closure, as shown in the drawings. Contact 52 is electrically connected as by a film firing lead wire 53 to a means'for providing an electrical impulse (not shown). Any means for providing such an impulse at the desired time may be utilized. One example of such means is in the piczo-electric crystal means commonly mounted in the ogival nose-pieces of projectiles or missiles and adapted to generate an electrical impulse upon contact of such projectiles or missiles with a target.

In the assembly of the arming mechanism, case 12 is closed at the rear end, as by closure 44, spring 48 is positioned on stake 46 and the arming device assembly comprising the sleeve 14 and attached rotary arming device R (in an unarmed, ready condition) is slid into the forward end of case 12 so that the forward end of spring 48 is positioned in depression 21 of the pellet 20 and so that pins 34 enter the elongated open ended groove 36. The assembly is then pushed rearwardly until the pins are positioned in the forward portion 38 of the groove and the assembly is then shifted angularly to guide the pins into the short groove section 48. Spring 46 then pushes the sleeve assembly forward to hold it in the position shown in Fig. 2. Forward closure 50 carrying contact 52 is then appropriately fastened to case 12, to seal the arming mechanism. A circular locking ring 56 is attached to the forward end of closure 50 and is of resilient construction and of a size whereby when case 12 is pushed into the arming mechanism housing 8 the locking ring will deform to allow relative movement of the walls of housing 8 and the case 12. When the case 12, containing the arming mechanism is pushed completely into operative position (as in Fig. l) the ring 56 prevents retrograde motion thereof and holds it in said position by pressing against the inner wall of housing 8, as shown in Fig. 1.

In practice, the structure is assembled as described, within a warhead with the sleeve 14 and the rotary arming device in the ready unarmed position, as shown in Figs. 1 and 2 and forms part of a conveying projectile such as a rocket. Upon launching of the rocket, the various parts thereof are subject to forces caused by an acceleration which continues substantially until the motive fuel of the rocket burns out. The effect of such acceleration is to cause movable components to be moved rearwardly by inertia or set-back forces. This setback force is effective to release rotary device R from its ready position to allow its timed rotation in response to continued acceleration. Simultaneously, sleeve 14, is moved rearwardly against, the pressure of setback spring 48, the grooves 40 riding pins 34 until the sleeve reaches the position of Fig. 3. For the period of acceleration during burning of the rocket fuel, sleeve 14 is retained in the position of Fig. 3, While rotor 26 is turning, in response to acceleration to a position in which bore 28 of the rotor is aligned with contact 52 (as in Fig. 4). After burn-out, the parts of the rocket are no longer subject to acceleration forces and spring 48 is efisstire. tm sh S e 4 orward p n 34 riding in the elongated zig-zag groove or delay track portion 36, whereby contact -2 may make electrical contact with the primer and train 30 in the bore 28 rotor 26. Subsequently, any electrical impulse fed into lead wire 53 causes initiation of primer and train 30 and detonation of booster pellet 20 to set off the main warhead charge 4 to cause explosion of said charge and fragmentation of the warhead. As previously stated, such an impulse may be provided by piezo-electric crystal means in the nose of the rocket, operated by contact of the rocket with a target, or by any other suitable means.

-It should be noted that the described device, from its ready position (Figs. 1 and 2) requires two distinct types of motion by rotor 26 and by sleeve 14 respectively before it can be completely armed and that the safety against accidental arming as by jolting in handling is greatly increased over that of prior known devices. As an added increment of safety the zig-zag nature of the path afforded by the short section 40 of groove 32 is notable, since by virtue of such construction the combination of a series of jolts (to allow each curve in the section to pass pins 34) accompanied by or causing a continuing acceleration would be necessary to cause sufiicient rearward motion of sleeve 14 to allow pins 34 to enter the longer arming portion 36 of groove 32.

It should also be noted that the operation of the parts is such that while the rotor 26 of arming device R is subject to forces causing it to rotate to arm the device R, the sleeve 14 must be in the set-back position of Fig. 3 and that it (sleeve 14) can move forward only after the acceleration forces are either no longer present or are so slight as to be overcome by the light spring 46. Thus, is is essentially true that sleeve 14 interposes a delay after arming of rotary arming device R, the delay depending on the burn-out time of the rocket and the nature of the zig-zag path 36 and strength of the spring 48. It therefore follows that even if arming device R should be accidentally caused to be prematurely moved to its armed position, normal operation of the sleeve 14 will not allow complete arming or ignition of the entire arming mechanism until the same desired delay has occurred as would occur without such a premature positioning of the device R. Meanwhile, any danger of the device R causing initiation of booster pellet 20 is obviated by virtue of the fact that device R is kept out of contact with the electrical initiating means 52.

From the foregoing it should be obvious that this invention provides a simple, efiicient arming mechanism having a greatly increased factor of safety against premature and accidental arming as compared with prior known device s.

While only a single illustrative example of a device according to this invention has been specifically described herein, it is obvious that many variations and modifications thereof are possible within the scope of the teachings of this disclosure. It is therefore to be understood that the scope of the invention is not intended to be limited by the specific illustrative example described but rather by the scope and language of the appended claims.

What is claimed is:

1. A fuze mechanism comprising a cylindrical tubular casing adapted to be housed Within the warhead of a missile, a closure member having a central opening at the forward end of said casing; a firing contact insulatively mounted in and sealing said central opening, a rotary acceleration operated arming device having an explosive train which is operable to be aligned with said firing contact upon arming of said rotary device by the application of forces caused by forward acceleration, said rotary device being mounted on a carriage member which is slidably supported within said casing for longitudinal motion in a direction towards and away from said firing contact, said carriage member consisting of a hollow cylindrical sleeve member having a forward end wall with a centrally located passage therethrough, the hollow interior and central passage of said carriage member containing a pellet of explosive material, said pellet having a cup-shaped depression formed in the rear end thereof, the cup-shaped end of said pellet being sealed within said carriage member by means of a thin cup-shaped metallic shield, the central passage in the forward end of said carriage member also being sealed with a thin metallic shield, a closure member at the rear end of said casing having a central stake attached to the inner side thereof for supporting and positioning a spring member which extends into the cupshaped depression formed in rear end of said explosive pellet and its shield, said spring member operable to exert a forward pressure on said carriage member through the explosive pellet, means releasable by acceleration forces caused by acceleration in a forward direction for locking said carriage member in a position in which said rotary device is displaced from said firing contact, and operative after such release to force said carriage member forward towards the forward end closure of said casing, whereby acceleration of the fuze mechanism in the forward direction causes the explosive train of the rotary arming device to align itself with the firing contact and the carriage member to be released and pushed towards said firing contact so that the firing contact contacts the explosive train to fully arin the fuze mechanism for firing by application of an impulse to and through said firing contact.

2. A fuze mechanism according to claim 1 wherein the central passage in the forward wall of said carriage member is adapted to communicate the interior of the carriage with the explosive train carried in the bore of the arming device when the arming device is in its armed position, whereby said explosive pellet is adapted to be ignited by said explosive train when the latter is fired by said firing contact.

3. A fuze mechanism according to claim 1 wherein said means for releasably locking said slidable carriage prior to acceleration and for forcing it toward said forward end closure after acceleration, comprises said spring means acting on the rear of said carriage member to normally bias it toward said forward end closure, and cooperating pin and groove means on the interior of said casing and on the exterior of said carriage member, said groove means comprising at least one V-shaped groove having an enlarged and forwardly disposed point and in which an arm of the V is substantially shorter than the other and closed at its free end, whereby with the cooperating pin disposed in said shorter arm said spring means is effective to hold said carriage locked in position with the pin disposed against the closed end of said shorter arm, and whereby the application of acceleration forces caused by forward acceleration will cause set back of said carriage to cause it to move rearwardly against the pressure of said spring means so that the pin means and groove means have such motion relative to one another as to dispose the pin the point of the V-shaped groove means so that upon termination of acceleration and of the forces resulting therefrom the spring means is effective to push the carriage member forwardly with the pin situated in the longer arm of the V-shaped groove means to permit the carriage means to approach said forward end closure and said firing contact.

References Cited in the file of this patent UNITED STATES PATENTS 1,311,104 Watson July 22, 1919 1,316,607 Watson Sept. 23, 1919 2,595,757 Brandt May 6, 1952 2,700,934 Thompson Feb. 1, 1955 2,709,962 Funk et al. June 7, 1955 2,712,284 Thomas July 5, 1955 

